* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 20px;
        }

        .container {
            background: white;
            border-radius: 20px;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
            max-width: 900px;
            width: 100%;
            padding: 40px;
        }

        h1 {
            color: #333;
            margin-bottom: 10px;
            font-size: 2em;
        }

        .subtitle {
            color: #666;
            margin-bottom: 30px;
            font-size: 0.95em;
        }

        .controls {
            display: flex;
            gap: 20px;
            margin-bottom: 30px;
            flex-wrap: wrap;
        }

        .input-section {
            flex: 1;
            min-width: 250px;
        }

        .alphabet-select {
            min-width: 200px;
        }

        label {
            display: block;
            color: #555;
            font-weight: 600;
            margin-bottom: 10px;
        }

        input[type="text"] {
            width: 100%;
            padding: 15px;
            border: 2px solid #e0e0e0;
            border-radius: 10px;
            font-size: 1.1em;
            transition: border-color 0.3s;
        }

        input[type="text"]:focus {
            outline: none;
            border-color: #667eea;
        }

        select {
            width: 100%;
            padding: 15px;
            border: 2px solid #e0e0e0;
            border-radius: 10px;
            font-size: 1.1em;
            background: white;
            cursor: pointer;
            transition: border-color 0.3s;
        }

        select:focus {
            outline: none;
            border-color: #667eea;
        }

        .output-section {
            background: #f8f9fa;
            border-radius: 10px;
            padding: 20px;
            min-height: 150px;
        }

        .output-title {
            color: #555;
            font-weight: 600;
            margin-bottom: 15px;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .copy-btn {
            background: #667eea;
            color: white;
            border: none;
            padding: 8px 16px;
            border-radius: 6px;
            cursor: pointer;
            font-size: 0.9em;
            transition: background 0.3s;
        }

        .copy-btn:hover {
            background: #5568d3;
        }

        .copy-btn:active {
            transform: scale(0.95);
        }

        .result {
            color: #333;
            line-height: 2;
            font-size: 1.05em;
            word-wrap: break-word;
        }

        .separator {
            color: #999;
            margin: 0 4px;
        }

        .letter {
            color: #000;
        }

        .number {
            color: #2196F3;
            font-weight: 600;
        }

        .special {
            color: #f44336;
            font-weight: 600;
        }

        .empty-state {
            color: #999;
            font-style: italic;
            text-align: center;
            padding: 40px 20px;
        }

        .info-box {
            background: #e7f3ff;
            border-left: 4px solid #2196F3;
            padding: 15px;
            margin-top: 20px;
            border-radius: 5px;
            font-size: 0.9em;
            color: #555;
        }

        .legend {
            display: flex;
            gap: 20px;
            margin-top: 15px;
            flex-wrap: wrap;
        }

        .legend-item {
            display: flex;
            align-items: center;
            gap: 8px;
            font-size: 0.9em;
        }

        .legend-color {
            width: 20px;
            height: 20px;
            border-radius: 4px;
        }

        @media (max-width: 600px) {
            .container {
                padding: 25px;
            }

            h1 {
                font-size: 1.5em;
            }

            .controls {
                flex-direction: column;
            }
        }